Well, bad, I would say. My test configuration was: Asus GTX 980, Samsung 55 "7590er UHD TV and a 40" 6900er UHD TV. Of course I have selected your settings on TV (UHD Color, name PC) and via the HDMI 2.0 input makes it even with 60 Hz !!! Just not on this adapter. The maximum resolution is 1980x1080 in 60p. So neither 30 nor 60 Hz UHD!
The picture is also compared with the HDMI input very dark.
I would be interested, therefore, the full-bodied statement of another reviewer who unfortunately tells nothing about its configuration.
My tip for anyone who wants to buy a large graphics card are prepared per UHD Monitor:
GTX 970 and 980 to function both with UHD and 30 as well as 60 Hz. You have to try only possibly different cable. HDMI 2.0 cable there is no way - is an expensive marketing gimmick. Very well, there are differences in quality, which have nothing to do with the price. Good work for me HDMI cable from CSL Computer, but only up to a maximum at 60 Hz. 3m - then the screen can be controlled only with 30 Hz or the image comes off partially.
Only on TV remember: rename UHD Color ON, HDMI Input on PC! Then it will come with the 60Hz.